Sepsis remains a serious clinical problem, and there remains no effective clinical intervention for reversal of organ injury that results from sepsis. The central hypothesis for this application is that dysregulation of cytokine production during inflammatory states results in organ injury and increased mortality. Selective inhibition of individual cytokines has not proven to be an effective intervention in some clinically relevant animal models and in several human clinical trials; however, in the current application it is proposed that combinations of cytokine inhibitors may be more beneficial than single agents. In the current application, the mouse cecal ligation and puncture (CLP) model will be used as a clinically relevant and reproducible model of intraabdominal sepsis. In an elaborate series of experiments, mice will be subjected to either lethal or nonlethal CLP and inhibition of IL-1 with IL-1ra, inhibition of TNFa with soluble TNF receptor, inhibition of chemokines KC and MIP2 a with neutralizing antibodies, or inhibition of both TNF and IL-1 by administration of IL-10 or Lysofylline. The effects of these agents individually or in various combinations on mortality in the CLP mouse model will be examined. In addition, CLP will be performed in IL-8 transgenic mice that have high circulating levels of IL-8 and in p55 TNF receptor knockout mice to examine the effect of these manipulations on mortality in this sepsis model. The remainder of the studies focus on the lung as a target organ in sepsis. The penetration of the lung by the cytokine inhibitors will be examined using a bioassay system and lung homogenates. Another series of experiments will examine the reactivity of alveolar macrophages from mice after CLP, and the various cytokine and anticytokine treatments. The final Aim is to assess the capacity of the lung to mount an appropriate respone to an inflammatory stimulus or to clear pathogenic bacteria. These studies will involve intratracheal administration of either LPS or live bacteria versus vehicle and examination of lung injury and cytokine responses. The results of these experiments will then be used to design combination therapies in human clinical trials.